Top-pressure forging hammer



A ril 27, 1965 F. RIEMENSCHNEIDER ETAL 3,130,129

TOP-PRESSURE FORGING HAMMER Filed Oct. 19 1961 2 Sheets-Sheet 1 Iii 15 i ILI I l/l/mrl'llillllmwkllll A INVENTORF F Riemann/Sunder -HHasseZ A ril 27, 1965 F. RIEMENSCHNEIDER ETAL 3,180,129

TOP-PRESSURE FORGING HAMMER Filed Oct. 19, 1961 2 Sheets-Sheet 2 //v VENTORS F KiPmPnfic/Melde +11 Hamel BY Z United States Patent 3,180,129 TGP-PREdSURE FORGING HAMMER Fritz Riernenschneitler, Leverkusen, and Harald Hassel,

Opladen, Germany, assignors to Eumuco Alrtiengesellschatt fiir Iliaschiuenbau, Leverlmsen, Germany Filed lllct. 19, 1961, Ser. No. 146,289 9 Claims. ((11. 72453) This invention relates to a hammer for hammer forging and die forging, using a hydraulic drive for the ram, which is constructed as a hydraulically operated toppressure hammer.

Forging hammers are known which have two rams operating in opposite directions to one another and wherein the drive is effected by a pressure medium. The pressure medium can be compressed air, steam or a hydraulic medium. It has already been proposed to 0perate the two ram pistons each by means of a pressuretransmitting device, the pressure-transmitting devices, which operate by means of steam or pneumatically, being arranged separately from the hammer at any desired point. t

The invention relates to a top-pressure forging hammer which is constructed as a counterblow hammer, which is driven hydraulically and whose drive is eiiected by means of a liquid pump with constant delivery quantity.

The invention is characterized in that in the counterblow hammer there is interposed between the pump and the cylinder chambers of the pistons connected to each ram an oscillatable liquid system which is formed by a pressure liquid kept continuously under initial load. The cylinder chambers of the pistons of the two rams are connected to the common pressure liquid container. With this oscillatable liquid system, the oscillatory system consisting of the ram and the elastic pressure liquid volume is so coupled that the liquid acts on the inner an nular piston face for the return travel and acts on the two piston faces for the working travel with the difierence between the areas of the two piston faces providing the force for the working travel. In this way, the counterhammer is included in the hydraulic driving system with the pressure liquid volume as an oscillatory system.

The oscillatory system consisting of the two rams and the volume of pressure liquid and coupled by way of the effective piston faces of the pistons of the two rams,

effects the compression of the constant pump delivery and the non-uniform movement of the two rams, and in fact the time of the upward or downward stroke is to be less than the period of the natural oscillation, preferably half of the period of natural oscillation. For this purpose, the modulus of elasticity E of the pressure liquid, the coupling face f of one ram, the coupling face f of the other ram, the mass m of one ram, the mass m of the other ram, the volume of pressure liquid V and the time t for the upward or downward stroke are to be so adjusted to one another that the value is less than 211-. By coupling piston face, there is understood the piston face which is effective during the relevant stroke.

A counterblow hammer constructed in this way is particularly simple since no coupling separate from the drive is required, and it is superior in efficiency to known types of hammers.

In the counterblow hammer, Which'is operated bydraulically in the manner indicated, the cylinder chambers of the pistons of the two rams are in communication not only with the pressure liquid container but also with Patented Apr. 2.7, 1935 the supply container. Each pipe connected to the chambers situated above the pistons contains shutoff elements which are adapted to be controlled in opposite directions to one another dependent on the movement of the ram. Non-return valves are also arranged in each of these pipes. For compensating for strong-rebound impacts an automatic pressure controller permits changingover of the rams in the end return positions only when a predetermined liquid pressure has been reached.

For the horizontally operating counterblow hammer, it is important that the two rams always receive the same movement impulse. This can be achieved by coupling the hammer LO the hydraulic oscillatory system in such a manner that the two rams are controlled by a common distributing slide valve, whereby the blow only takes place when a predetermined pressure adjustable at a pressure controller is reached, and both rams always strike from the same end return position.

According to the invention, the latter is achieved in the case of the horizontally operating counterblow hammer and using the oscillatable liquid system in that both rams are automatically hydraulically adjustable into the same end return position. Advantageously, in order to adjust this position, the ram piston is followed by a seriesarranged braking piston 'on which is arranged a further piston for displacement up to an abutment. The abutment itself can be made adjustable for allowing for different die weights. As a result, the ram spacing can be adapted to the die heights.

The subject of the invention is illustrated with reference to two examples of embodiment in the drawings, wherein:

FIG. 1 shows a diagrammatic view of a vertically 'o I crating counterblow hammer according to the invention, partly in section, and 7 FIG. 2 is a diagrammatic view or" one form of embodiment of a horizontally operating counterblow hammer.

The counterblow hammer according to FIG. 1 comprises two rams Z and 3 which move upwards and downwards in a hammer frame 1 and which are connected by piston rods 4 and 5 to pistons 6 and 7. Chambers 8 and 9 of cylinders for the pistons and disposed below the pistons 6 and '7 are in open communication with a container it} containing an elastic pressure liquid volume.

From a constantelivery pump 11 a pipe 12 leads by way of a non-return valve 1.3 to the container Ill. The pump is connected in known manner to a by-pass pipe 15 which can be controlled by a shutofi element 14. From the container 16, a pipe 16 leads by way of a reversing distributing slide valve 1'7 into a cylinder chamber 18 and a pipe 19 through the reversing valve 1'7 and a non-return valve 29 into a chamber 21. The cylinder chamber 13 is also connected to the container 10 by way of a non-return valve 22. The cylinder chamber 18 can also be connected by way of the reversing valve 17, a shutoff valve 2.3, and a pipe 24 to a supply container 25. The same applies to the cylinder chamber 21.

Cylinder chambers 26 of intercepting pistons 27 are in communication through a non-return valve 23 with the container 10 and through a non-return valve 2% with the supply container 25.

A pressure controller 30 is connected through a safety valve 31 and the pipe 12 to the container It).

The counterblow hammer according to the invention operates in the following manner:

The pump 11 deliversuninterruptedly both during the working stroke and also during the return stroke with a constant delivery quantity into the container 10. It is switched to pressureless circulation through the circuit including pipes 15 and shutoff element 14 only when the rams 2 and 3 are to remain stationary. When the rams means 7 3 are in the end return position, the pressure in the pressure liquid container increases until the pressure controller 30 responds, and operates the reversing valve 17 and the shutoff valve 23 in such a manner that the cylinder chambers 8, 9 and 18 are in communication with the pressure liquid container 10 whereas the cylinder chamber 21 is connected to the supply container 25. As a result, the lower ram is accelerated upwards against its own weight by the pressure on the entire lower piston face, while the upper ram falls and additionally is accelerated downwards with the pressure on the face corresponding to the piston rod cross-section.

Shortly before impact, one of the two rams operates a preferably electric tripping device for the reversing valve 17 which operates this valve in such a manner that the cylinder chambers 8, 9 and 21. are connected to the container 1t) and the cylinder chamber 18 is connected to the supply container 25. As a result, the upper ram is lifted by the pressure on the lower annular face of the piston 6. The lower ram falls by its own weight in opposition to the pressure on the surface corresponding to the piston rod cross-section.

Before. the upper end position of the upper ram, the upper ram operates preferably an electric tripping device for the shutoff valve 23 which closes the said valve. The pressure liquid in the chamber 18 must now be forced through the non-return valve'22 into the container 19. As a result, and owing to its own weight, the upper ram is braked and brought to a stop. Since during this phase of the stroke the inflow of pressure liquid from the chambers l3 and i into the pressure container MB is substantially greater than the outflow into the chambers 8 and 2.1 and also the pump delivers into the pressure container, the pressure increases so strongly that the lower ram is also braked. In the end position of the ram 3, the pressure in the chambers 9 and 21 is accordingly so great that the ram would immediately ascend again, but it is prevented from doing so by the non-return valve which blocks the outflow of the pressure liquid from the chamber 21.

Since, owing to the occurrence of strong-rebound impacts the falling energy of the lower ram cannot always be taken up, the intercepting pistons 27 are situated shortly before the end position of the ram. These have the advantage over known buflfers which annul the rebound energy by damping action, that they convert the residual energy of the ram 3 into compression energy for the pressure liquid in the container 19. This energy is available for the next blow.

The rams then remain stopped until the pressure set at the pressure controller 30 is reached, and the cycle begins again.

Since, when using different dies, it is often desirable to reduce the number of impacts, this can be achieved by automatically temporarily switching the circuit device to by-pass flow during the return stroke by means of an electric timing relay.

The horizontally operating counterblow hammer shown in FIG. 2 comprises two pistons 2 and 3 which are movable in the frame 1 and which are connected by the piston rods 4 and 5 to the pistons 6 and 7. Chambers 33 and 34 between ram and pistons are in open communication with the container accommodating the elastic pressure liquid volume.

From a pump 11 with constant delivery quantity, a pipe 35 leads through a non-return valve 36 to the container 10. The pump is connected in known manner. to a bypass pipe 38 which can be controlled by a shutoff element 37. From the container 10, a connection goes by way of a pipe 39 and a pipe 40 to the cylinder chambers 33 and 34. From the pump 11 and pipe 41 leads through a valve 42 and then through a pipe 43 to the cylinders 44 and 45 situated at the outer sides of the pistons and 7.

The pistons 6 and 7 are followed by further pistons 45 and 47 to which pistons 48 and 49 are connected. Cyliner chambers 59 and 51 communicate through pipes 52 and 53 with a supply container 54 and the container 10. The cylinder chambers 55 and 56 are connected through the pipe 4!) to the container 10. By way of non-return valves 57 and 58 the pressure liquid is forced from the chambers 59 and 51 into the container 10. By way of no-return valves 59 and 60 pressure liquid is sucked from the supply container. 54' into the chambers 50 and 51.

A pressure controller 62 and safety valve 63 are connected to a pipe 61 which leads from the pipe 39 to the supply container.

The constantly identical end return position is obtained by braking by means of the pistons 46 and 47. The pistons 48 and 4% cause the pistons 6 and 7 of the rams 2 and 3 to advance again until the pistons 46 and 47 come to abut on abutments 64 and 65. As a result, the rams 2 and 3 always move into the same starting position as a pre-requisite for imparting an always identical movement impulse to the two rams. Theabutments 64 and 65 can be arranged to be displaceable and adjustable in the direction of the piston axes. Various intensities of impact can be obtained by adjusting the pressure at the pressure controller 62.

The horizontal counterblow hammer operates in the following manner:

The pump 11 delivers uninterruptedly with a constant delivery quantity into the container 19. i It is switched to pressureless circulation through the circuit 37, 38 only when the rams 2 and 3 are to remain stationary. When the rams are in the end return position the pressure in the pressure liquid container 10 increases until the pressure controller 62 responds. This moves the valve slide of the reversing valve 42 towards the left and thereby connects the cylinder chambers 44 and 4-5 through the pipes 35 and 43 to the container 10. The cylinder chambers 33 and 34 are constantly in communication with the container 10 through the pipes 33 and 40. Since the entire piston face in the chambers 44 and 45 receives pressure in the chambers 33 and 34 only an annular surface receives pressure, the rams 2 and 3 are accelerated towards the middle. Shortly before impact, by means of a preferably electro-hydraulic tripping device, the reversing valve 42 is changed back into the illustrated starting position. The chambers 44 and 45 are thus again connected to the supply container 54 through the pipe 43 and the reversing valve 42. The rams 2 and 3 move backwards. The chambers 44 and 45 empty into the supply container 54. In the end position, the rams 2 and 3 are braked by the pistons 46 and 47, which have considerably larger crosssectional surfaces than the ram pistons 6 and 7. The rams pass beyond the end position. The pressure liquid from the chambers 50 and 51 escapes through the non-return valves 57 and 58 into the pressure container 10 and compresses the volume of pressure liquids. The braking energy is thereby made usable for the following blow. The cross-sectional surfaces of the pistons 48 and 49 are somewhat larger than the annular piston surface in the chambers 8 and and since the chambers 8, 9, 55 and 56 constantly receive pressure through the pipes 39 and 49, the rams are then slowly pushed back into the initial position, i.e. until the piston 46 and 47 bear against the abutments 64 and 65. The ram speed is regulated by throttle means (not shown) in the supply piping to the chambers 55 and 56. The chambers 50 and 51 suck in a full supply of pressure liquid through the non-return valves 59 and 60. The pressure in the container 10 then increases until the pressure controller 52 responds and a new cycle begins.

Although preferred embodiments of the invention have been disclosed, it is to be understood that minor modifications may be made within the scope of the invention, as defined in the appended claims.

'What is claimed as new is:

1. In a top forging hammer of the counterblow type comprising a pair of opposed rams movable towards each system for said rams including a constant delivery pump,

said hydraulic system including an oscillatory hydraulic system between said pump and said pistons and including a pressure liquid completely filling a liquid container containuously under an initial load and acting as a hydraulic spring, said pistons having working surfaces of greater area than their return surfaces, said liquid container and oscillatory hydraulic system being in open cornrnunication with at least one of said cylinders for apply ing a force on said return face of the respective piston to urge said last mentioned piston to a retracted position with the pressure on said return face being over-balanced by selected pressure on said working face to operate said last mentioned piston.

2. The forging hammer of claim 1 wherein said one cylinder has the working face end thereof connected to said container by a non-return valve.

3. The forging hammer of claim 1 wherein the connection between the hydraulic system and said one cylinder working end includes a pressure responsive control device for efiectintg flow of hydraulic fluid to said one cylinder working end after the hydraulic fluid reaches predetermined pressure only.

The forging hammer of claim 1 wherein said ham mer is vertically disposed and said rams are vertically movable, and including means for converting the residual energy of the lower falling ram into pressure within said container for use in the next cycle of operation of said hammer.

5. The forging hammer of claim 4 wherein said means includes said lower ram having at least one braking piston and cylinder associated therewith and connect through a non-return valve to said container.

6. The forging hammer of claim 1 wherein both of said cylinders are connected to said oscillatory hydraulic system.

7. The forging hammer of claim 1 wherein both of said cylinders are connected to said oscillatory hydraulic system, with said oscillatory hydraulic system and said liquid filled container applying a hydraulic spring force on said return faces of the pistons thereof.

8. In a top forging hammer of the counterblow type comprising a pair of horizontally disposed rams movable towards each other including pistons mounted in cylinders, including a constant delivery pump and an oscillatory hydraulic system between said pump and said pistons, said system including a relatively large liquid container completely filled with liquid under pressure continuously un der an initial load and acting as a hydraulic spring, said pistons having Working surfaces greater than their return surfaces, said oscillatory hydraulic system being in open communication with said liquid container for applying a force on the return surface of a piston to urge that piston to a retracted position, with the pressure on said return surface being overbalanced by selected pressure on the working face too perate that piston, and a common slide valve controlling liquid flow to said pistons.

9. The forging hammer of claim 8 wherein a braking piston is disposed in series with each of said pistons and coupled to the container for transmitting the braking force to said container by way of fluid under pressure.

References Cited by the Examiner UNITED STATES PATENTS 2,220,037 10/40 Fitzgerald 78-25 2,619,072 11/52 Clarke 78-42 2,770,222 11/56 Anderson l2l38 2,785,535 3/57 Alcorn 78-42 2,800,110 7/57 Haarrneyer.

2,920,607 1/60 Barkan.

WILLIAM I. STEPHENSON, Primary Examiner. WILLIAM W. DYER, 1a., Examiner. 

1. IN A TOP FORGING HAMMER OF THE COUNTERBLOW TYPE COMPRISING A PAIR OF OPPOSED RAMS MOVABLE TOWARDS EACH OTHER INCLUDING PISTONS MOUNTED IN CYLINDERS, A HYDRAULIC SYSTEM FOR SAID RAMS INCLUDING A CONSTANT DELIVERY PUMP, SAID HYDRAULIC SYSTEM INCLUDING AN OSCILLATORY HYDRAULIC SYSTEM BETWEEN SAID PUMP AND SAID PISTONS AND INCLUDING A PRESSURE LIQUID COMPLETELY FILLING A LIQUID CONTAINER CONTINUOUSLY UNDER AN INITIAL LOAD AND ACTING AS A HYDRAULIC SPRING, SAID PISTONS HAVING WORKING SURFACES OF GREATER AREA THAN THEIR RETURN SURFACES, SAID LIQUID CONTAINER AND OSCILLATORY HYDRAULIC SYSTEM BEING IN OPEN COMMUNICATION WITH AT LEAST ONE OF SAID CYLINDERS FOR APPLYING A FORCE ON SAID RETURN FACE OF THE RESPECTIVE PISTON TO URGE SAID LAST MENTIONED PISTON TO A RETRACTED POSITION WITH THE PRESSURE ON SAID RETURN FACE BEING OVER-BALANCED BY SELECTED PRESSURE ON SAID RETURN FACE BEING OVER-BALANCED LAST MENTIONED PISTON. 